{{Short description|Zeolite mineral}} {{Infobox mineral | name = Pollucite | category = Tectosilicate minerals | group = Zeolite group | boxwidth = | boxbgcolor = | image = Pollucite-193819.jpg | imagesize = 260px | caption = Euhedral, tabular crystal of colorless, translucent and lustrous pollucite with frosted crystal faces from Afghanistan (size: 2.7 x 2.4 x 1.2 cm) | formula = {{chem2|Cs(Si2Al)O6*''n''H2O}} | IMAsymbol = Pol<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3 |pages=291–320|doi=10.1180/mgm.2021.43 |bibcode=2021MinM...85..291W |s2cid=235729616 |doi-access=free}}</ref> | strunz = 9.GB.05 | dana = 77.1.1.2 | system = Isometric | class = Hexoctahedral (m{{overline|3}}m) <br>H-M symbol: (4/m {{overline|3}} 2/m) | symmetry = ''Ia{{overline|3}}d'' | unit cell = a = 13.67&nbsp;Å; Z&nbsp;=&nbsp;16 | color = Usually colorless; also white, grey, pink, blue or violet | habit = Usually massive; rare crystals are normally trapezohedral or cubic | twinning = | cleavage = None observed | fracture = Conchoidal to uneven | tenacity = Brittle | mohs = 6.5 to 7 | luster = Vitreous to greasy | refractive = 1.508–1.528 | opticalprop = Isotropic or very weakly anisotropic | birefringence = | pleochroism = | streak = White | gravity = 2.7 to 3.0 | density = | melt = | fusibility = | diagnostic = | solubility = Readily soluble in HF; dissolves with difficulty in hot HCl | diaphaneity = Transparent to translucent | other = Sometimes weakly fluorescent under SW and LW UV | references = <ref>[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Pollucite Mineralienatlas]</ref><ref name = Dana>Gaines, et al. (1997) ''Dana's New Mineralogy,'' Wiley {{ISBN|978-0471193104}}</ref><ref name = Mindat>[http://www.mindat.org/min-3255.html Pollucite on Mindat.org]</ref><ref name = Webmin>[http://webmineral.com/data/Pollucite.shtml Pollucite data on Webmineral]</ref><ref name = HOM>[http://rruff.geo.arizona.edu/doclib/hom/pollucite.pdf Handbook of Mineralogy]</ref>}}

'''Pollucite''' is a zeolite mineral with the formula {{chem2|(Cs,Na)2Al2Si4O12*2H2O}} with iron, calcium, rubidium and potassium as common substituting elements. It is important as a significant ore of caesium and sometimes rubidium. It forms a solid solution series with analcime. It crystallizes in the isometric-hexoctahedral crystal system as colorless, white, gray, or rarely pink and blue masses. Well-formed crystals are rare. It has a Mohs hardness of 6.5 and a specific gravity of 2.9, with a brittle fracture and no cleavage.

==Discovery and occurrence== [[File:Pollucite-RoyalOntarioMuseum-Jan18-09.jpg|thumb|left|A pollucite ore sample held in the Royal Ontario Museum]] It was first described by August Breithaupt in 1846 for occurrences on the island of Elba, Italy. It is named for Pollux, the twin of Castor on the grounds that it is often found associated with petalite (previously known as ''castorite'').<ref>{{cite journal | url = http://gallica.bnf.fr/ark:/12148/bpt6k15154k.image.f443.langFR | doi = 10.1002/andp.18461451111 | journal = Annalen der Physik und Chemie | year = 1846 | volume = 69 | page = 439&ndash;442| first = August | last = Breithaupt | title = Neue Mineralien | issue = 11|bibcode = 1846AnP...145..429B }}</ref> The high caesium content was missed by the first analysis by Karl Friedrich Plattner in 1848,<ref>{{cite journal | doi = 10.1002/andp.18461451112 | title = Chemische Untersuchung zweier neuen, vom Herrn Prof. Breithaupt mineralogisch bestimmten Mineralien von der Insel Elba | year = 1846 | last1 = Plattner | first1 = C. F. | journal = Annalen der Physik und Chemie | volume = 145 | issue = 11 | pages = 443–447|bibcode = 1846AnP...145..443P | url = https://zenodo.org/record/1423614 }}</ref> but after the discovery of caesium in 1860 a second analysis in 1864 was able to show the high caesium content of pollucite.<ref>{{cite journal | url =http://gallica.bnf.fr/ark:/12148/bpt6k3015d.image.f716.langFR | first = F. | last = Pisani | title = Étude chimique et analyse du pollux de l'ile d'Elbe | journal = Comptes rendus | volume = 58 | pages = 714&ndash;716 | year = 1864}}</ref>

Its typical occurrence is in lithium-rich granite pegmatites in association with quartz, spodumene, petalite, amblygonite, lepidolite, elbaite, cassiterite, columbite, apatite, eucryptite, muscovite, albite and microcline.

About 82% of the world's known reserves of pollucite occur near Bernic Lake in Manitoba, Canada, where they are mined for their caesium content for use in caesium formate oil drilling assistance.<ref>http://www.encyclopedia.com/doc/1G1-75752682.html Original reference to ''Mining Journal'', March 2, 2001, p 160. Accessed March 28, 2009. (dead link 15 February 2022)</ref> This ore is about 23%<ref>{{cite book |title=Cesium |last=Harris |first=Keith L. |publisher=US Department of the Interior, Bureau of Mines |year=1979}}</ref>{{rp|1}} to 25%<ref>{{cite book |last1=Nichols |first1=Ivan L. |first2=Karl C. |last2=Dean |title=Volatilization of Cesium Chloride from Pollucite Ore |volume=6780 |publisher=US Department of the Interior, Bureau of Mines |year=1966}}</ref>{{rp|2}} caesium by weight.

==References== {{Reflist}}

{{Commons category}}

Category:Caesium minerals Category:Sodium minerals Category:Aluminium minerals Category:Zeolite group Category:Cubic minerals Category:Minerals in space group 230 Category:Luminescent minerals